Combustion method and apparatus

Abstract

Unreacted gas generated at outside is introduced through a gas inlet tangentially into a secondary combustion chamber with a substantially cylindrical side wall, so that a spiral ascending flow of the unreacted gas is generated in the chamber. A bulk material in the chamber is blown up by the unreacted gas introduced through the gas inlet to be circulated in the chamber so as to substantially completely burn unburnt solids entrained in the unreacted gas.

What is claimed is: 
     
       1. A combustion apparatus comprising a fluidized bed type primary combustion chamber, a secondary combustion chamber provided separately from the primary combustion chamber, a gas inlet for tangentially guiding unreacted gas with unburnt solids entrained therein generated in the primary combustion chamber and secondary air to a lower portion of a side wall of the secondary combustion chamber, a medium circulation passage for connecting a medium outlet on a lower end of the primary combustion chamber to the side wall of the secondary combustion chamber and a medium outlet on a hopper at the lower portion of the secondary combustion chamber connected to the primary combustion chamber, wherein a position of connecting the medium circulation passage to the side wall of the secondary combustion chamber is higher than a position of connecting the gas inlet to the side wall of the secondary combustion chamber. 
     
     
       2. The apparatus according to claim 1, wherein the secondary combustion chamber is provided above the primary combustion chamber. 
     
     
       3. The apparatus according to of claim 1, wherein the secondary combustion chamber has therein a lower complete combustion zone above the hopper as well as an upper chemical agent reaction zone, a chemical agent injection nozzle being mounted on the side wall of the secondary combustion chamber at a boundary between the zones so as to inject a denitrating agent. 
     
     
       4. The apparatus according to claim 1, wherein the secondary combustion chamber has therein a lower complete combustion zone above the hopper as well as an upper chemical agent reaction zone, a chemical agent injection nozzle being mounted on the side wall of the secondary combustion chamber at a boundary between the zones so as to inject a desulfurizing agent. 
     
     
       5. A combustion method comprising the steps of: tangentially guiding unreacted gas admixed with air, with unburned solids entrained therein from a primary combustion chamber to a lower portion of a side wall of a generally cylindrical secondary combustion chamber;   generating a spiral ascending flow of the unreacted gas in the secondary combustion chamber to ensure a predetermined retention time of the gas so that the gas is completely burned;   forming a group of unburned solids with elevated particle concentration along the side wall of the secondary combustion chamber by centrifugal force of the spiral ascending flow which are flown upwardly by the combustion gas for circulation; and   charging a fluidization medium into the side wall of the secondary combustion chamber to contact the medium with said group so that the fluidizing medium accompanies the group of the unburned solid with the elevated particle concentration, thereby contacting the unburned solids with the medium and completely burning the unburned solids.